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The purpose of the Oracle
Hardware Assisted Resilient Data (HARD) initiative is to prevent
data corruptions before they can occur. When HARD is enabled, the
OCR writes what are known as HARD-compatible blocks.
While data corruptions are rare,
they can have a catastrophic effect on a database, and by extension,
on the business it supports. By providing Oracle's data validation
algorithms to disk manufacturers and having these algorithms at work
inside storage devices, Oracle, with disk vendor support, will
prevent corrupted data from being written to the database files on
permanent storage. This type of end-to-end high-level software to
low-level hardware validation is currently a unique capability
provided only by Oracle and its storage partners. Oracle program
algorithms validate and add protection information to the database
blocks and once passed to the disk, the protection information is
validated by the HARD compliant storage device. In this manner, HARD
prevents corruptions from being introduced into the I/O path between
the database and storage and therefore eliminates a large percentage
of failures that the database industry has previously not been able
to prevent. While RAID, in its many flavors (0, 1, 1+0, 5) has
gained a wide following with system operators by ensuring the
physical protection of data, the HARD algorithm implementation takes
data protection to the next level by going beyond protecting
physical bits, to protecting business data.
The HARD algorithms were first
made available in the Oracle9i Database and have been extended into
the Oracle Database 10g. The validation in Oracle Database 10g is
more comprehensive and all file types and blocks are inoculated by
HARD including database files, online logs, archive logs and
backups. In addition the use of ASM enables HARD without having to
use raw disk devices. With the cooperation of hardware vendors HARD
support is being offered in conjunction with many of the major
storage arrays.
The classes of data corruptions
that Oracle addresses with HARD include:
* Writes of physically and
logically corrupt blocks
* Writes of blocks to incorrect
locations
* Erroneous writes by programs
other than Oracle to Oracle data
* Partially written blocks
* Lost writes
* Corrupted third party backups
The HARD initiative includes
several algorithms that will be embedded in Oracle storage partner?s
storage devices to prevent all these classes of corruptions. These
algorithms will be rolled out in stages by Oracle's storage partners
over time.
The following companies have
joined the HARD initiative as of this writing:
* EMC
* Compaq
* Fujitsu
* Hewlett Packard
* Hitachi
* NEC
* Network Appliance
* Sun Microsystems
* VERITAS
* IDC
HARD Validated Products
HARD Test Kit Version 2.2 for
Oracle9i Release 2
Validation Description
Hitachi SANRISE 9900V/Lightning
9900V (DB Validator)
HP Surestore xp1024
NEC iStorage Disk Array
Sun StorEdge 9900
Checks for writes of corrupted
datafile blocks. This includes the checksum value as well as
validation of selected fields in the block.
4 (out of 5 possible checks)
4 (out of 5 possible checks)
5 (out of 5 possible checks)
4 (out of 5 possible checks)
Checks for writes of corrupted
redo log blocks. This includes the checksum value as well as
validation of selected fields in the block.
3 (out of 4 possible checks)
3 (out of 4 possible checks)
4 (out of 4 possible checks)
3 (out of 4 possible checks)
Checks for writes of corrupted
controlfile blocks. This includes the checksum value as well as
validation of selected fields in the block.
4 (out of 5 possible checks)
4 (out of 5 possible checks)
5 (out of 5 possible checks)
4 (out of 5 possible checks)
Check for writes of Oracle data
that is not a multiple of Oracle blocksize for target device.
Yes
Yes
Yes
Yes
HARD Test Kit Version 2.1 for
Oracle8i and Oracle9i Release 1
Validation Description
Hitachi SANRISE 9900V/Lightning
9900V (DB Validator)
HP Surestore xp1024
Sun StorEdge 9900
Checks for writes of corrupted
datafile blocks. This includes the checksum value as well as
validation of selected fields in the block.
4 (out of 5 possible checks)
4 (out of 5 possible checks)
4 (out of 5 possible checks)
Checks for writes of corrupted
controlfile blocks. This includes the checksum value as well as
validation of selected fields in the block.
4 (out of 5 possible checks)
4 (out of 5 possible checks)
4 (out of 5 possible checks)
Check for writes of Oracle data
that is not a multiple of Oracle blocksize for target device.
Yes
Yes
Yes
HARD Test Kit Version 1 for
Oracle8i
Validation Description
EMC Symmetrix (Double Checksum)
Checks the checksum value of an
Oracle data block on write.
Yes
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